Method of making a metal grating



July 15, 1969 A. MENTI S 3,

METHOD OF MAKING METAL GRATING Filed May 9, 1967 United States Patent 01 fice 3,455,005 Patented July 15, 1969 METHOD OF MAKING A METAL GRATING Andrew Mentis, 96 Kloof Road, Bedfordview, Johannesburg, Transvaal, Republic of South Africa Filed May 9, 1967, Ser. No. 637,163

Claims priority, application Republic of South Africa, May 20, 1966, 66/2,912

Int. Cl. B2311 15/12 US. Cl. 29-160 Claims ABSTRACT OF THE DISCLOSURE A metal grating consisting of bearer bars and crossstays, the latter being of originally circular cross-section and fitted through corresponding holes in the bearer bars. The cross-stays are thereafter flattened between the bearer bars in planes parallel to the bearer bars and finally rotated through 90.

This invention relates to gratings of the type used as metal flooring stair treads and the like, and to the method of making such gratings.

Many forms of grating have been proposed and one form which has recently become generally available utilizes bearer bars supporting cross-stays having a depth approximately twice that of their width. This type of grating generally has the cross-stays secured in slots in the upper edges of the bearer bars and both the notching of the bearer bars and flattening of the rod to form the cross-stays leads to undesirable deformations which must be corrected before satisfactory gratings can be made.

It is the object of the present invention to provide a grating which will not be subject to appreciable deformation of the material from which it is made, and also to provide an economical method for the manufacture of such grating.

According to this invention there is provided a metal grating comprising parallel bearer bars, spaced lines of holes through the bearer bars and adjacent the edges of the bars at one side of the grating, and cross-stays having portions of complementary cross-section to that of the holes located in the latter, and portions of different crosssection extending between the bearer bars.

The invention also provides for the portions of the cross-stays between the bearer bars to be of rectangular section with a depth substantially twice the width thereof.

Further features of this invention provide a method of manufacturing gratings of the type set forth comprising arranging prepunched bearer bars in a jig, threading crossstays through the bearer bars, passing the portions of the cross-stays extending between the bearer bars between flattening rolls, and subsequently rotating the cross-stays to locate the planes of the flattened surfaces of the cross stays transverse to the lengths of the bearer bars.

The invention is illustrated diagrammatically in the accompanying drawing in which:

FIG. 1 is a plan view partly in section of the grating according to this invention,

FIG. 2 is a section of the grating on the line A-A in FIG. 1,

FIG. 3 is a section of the grating on the line BB in FIG. 1,

FIG. 4 illustrates a method of flattening the cross-stays,

FIG. 5 is a front elevation of the feed roll shown in FIG. 4 and FIG. 6 illustrates the method of rotating the flattened cross-stays through right angles.

As shown in FIGS. 1 to 3 the grating comprises bearer bars 1 located by cross-stays 2 extending through holes 3 of circular section in the bearer bars. The portions 4 of the cross stays in the holes 3 are of complementary circular cross-section to said holes, while the portions 5 of the cross-stays between the bearer bars are of flattened section. As shown clearly in FIG. 3 the portions 5 of the cross-stays are generally of rectangular section but with the ends tapering to meet the portions 4.

The portions 5 of the cross-stays being of greater height than the diameter of the portions 4 act to locate the bearer bars in spaced relationship, but this location is mainly effected by the swelling of the portions 4 so that they are a tight fit in the holes 3. This is effected automatically by the flattening of portion 5 causing sufiicient metal flow into portions 4 to effect the required location provided the clearances between the holes 3 and crossstays is not too great before the flattening operation.

The cross-stays 2 are shown in the drawing with the top edges thereof slightly below the level of the tops of the bearer bars 1. However, the cross-stays may be above or level with the tops of the bearer bars, this being controlled by the location of the holes 3 in the bearer bars and the degree of flattening of the cross-stays.

As an example of typical dimension of a grating according to this invention, the bearer bars 1 may be about 1 /2" deep and the cross-stays made from A drawn rod which has the portions 5 thereof flattened to a thickness of and a height of To manufacture the grating, the bearer bars 1 are punched at equal spacing to form the holes 3 and rods 6 threaded therethrough by any conventional means to form the basic grid structure 7 shown on the left hand side of FIG. 4.

This grid structure 7 is fed between flattening rolls 8 to reduce the rods 6 to an approximately rectangular section having a thickness approximately one half its width. This process locks the cross-stays 2 so formed against transverse movement relative to the bearer bars 1 and makes rotation of the cross-stays very difficult.

The grating is preferably formed upside down mainly to assist location of the bearer bars 1 before being locked to the cross-stays. The feeding of the grid structure 7 between the flattening rolls 8 is conveniently elfected by a feed roll 9 having transverse grooves 10 which engage the rods 6 in turn. The feed rolls 9 and flattening rolls 8 have deep circumferential grooves 11 through which the bearer bars 1 extend and are thereby located prior to being locked to the cross-stays 2.

The flattening of the cross-stays is a continuous operation and it will be noted from FIG. 4 that they are flattened at right angles to the direction required. The rotation of the cross-stays to the positions shown in FIGS. 1 to 3 is effected in a separate non-continuous operation as shown in FIG. 6.

As shown in FIG. 6, opposite edges of the portions 5 are engaged by die faces 12 of oppositely acting rams to rotate the cross-stays into the required position with the planes of the flattened portions 5 extending at right angles to the lengths of the bearer bars 1.

The method enables gratings to be made quickly, economically and with the components in an undistorted condition.

What I claim as new and desire to secure by Letters Patent is:

1. A method of making a metal grating, said method comprising forming equally spaced circular holes in elongated bearer bars, locating a plurality of said bearer bars in parallel spaced relationship, threading cross-stays through corresponding holes in the bearer bars, flattening the portions of the cross-stays between the bearer bars in planes extending substantially parallel to the lengths of the bearer bars, and thereafter rotating the flattened cross-stays through approximately 2. A method as claimed in claim 1 wherein the flattening of the portions of the cross-stays is effected by passing the bearer'bar and cross-stay assembly between flattening rolls.

3. A method as claimed in claim 1 in which the said portions of the cross-stays are flattened sufficiently to expand the remaining portions of the cross-stays into tight engagement.

4. A method as claimed in claim 3 in which the rotation of the flattened cross-stays is efiected by displacing opposite edges of the cross-stays in opposite directions.

5. A method as claimed in claim 4 wherein said opposite edges of the cross-stays are displaced by die faces of oppositely acting rams.

References Cited UNITED STATES PATENTS 1,734,660 11/1929 Williams et a1. 52667 X 1,867,702 7/1932 Keown 52667 ALFRED C. PERHAM, Primary Examiner U.S. Cl. X.R. 52-667 

